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Humanised milk Cloned cows that produce 'humanised' milk might be an interesting scientific achievement, but have been met with limited enthusiasm.

Chinese researchers announced in the journal PLoS ONE this week that they had engineered cows to secrete milk containing lysozyme, a protein found in human breastmilk that boosts the immunity of breastfed babies.

The researchers from the China Agricultural University and GeneProtein Biotechnology Company, both in Beijing, say alternatives to breastmilk are important because mothers are sometimes reluctant or unable to breastfeed.

"Modified bovine milk is a possible substitute for human milk," they write.

The researchers inserted human lysozyme genes into the nuclei of cow body cells, and then used somatic cell nuclear transfer (the 'Dolly method') to clone the cows.

Uncertain public support

New Zealand researcher, Dr Goetz Laible, of AgResearch has been involved with boosting nutrient levels in milk through transgenic cows.

He says the Chinese research builds on previous research in the US, which developed transgenic goats that produced milk with human lysozyme.

"I think it's great that the step has been taken to go from goat as a model into cattle," says Laible. "It might form a new base for an improved infant formula."

But he says, uncertain public support for the use of transgenic animals in food production means funding for such research has dried up.

"We are not actively working on this for funding reasons," says Laible, who now focuses instead on 'biopharming', the use of transgenic animals to produce therapeutic products, such as monoclonal antibodies.

Technical hurdles and ethics

David Nation from the Dairy Futures CRC in Melbourne says there is no active research on genetically modified cows in Australia.

"The dairy industry [in Australia] made a very definite decision to discontinue investment in transgenics because there are still lots of technical limitations and still large ethical issues to resolve with the community," he says.

The Chinese researchers implanted 312 blastocysts into cows. But only 37 full-term calves were born, of which many did not survive and only four were found to reach normal lactation.

Nation says previous research on transgenic cows in Australia found similar problems with calf mortality.

"That's considered one of the big unknowns in this technology," he says.

"Why is it in the cloning process that there is a significant number of abnormalities that lead to both abortions and low survival for those animals that do reach term?"

Nation says the problems are even more pronounced when the clone has been genetically modified.

Breastmilk substitute?

Breast milk experts are also dubious about this direction of research.

"This is an interesting scientific achievement but it really has little relevance to feeding babies," says Professor Peter Hartmann of the University of Western Australia.

He says lysozyme is only one of 279 proteins in human milk that provide protection to babies.

"The ones in Melbourne and in Western Australia are mainly for premature infants whose mothers do sometimes have trouble producing enough milk to start with. And they have more than enough donors," says Mortenson.

GM Salmon precedent

As for Laible, he would like to continue research on milk from transgenic cows, and is watching with interest to see if US regulatory authorities approve genetically modified salmon for human consumption.

"I think the outcome of that will of course be important for how this whole field is going," he says.

The US Food and Drug Administration (FDA) is currently considering whether Atlantic salmon engineered to grow faster than normal is safe to eat.

Consumer and environmental groups have expressed concern about the potential health and ecological effects of the fish. They claim there is a lack of expertise in food allergies, endocrinology and fish ecology among the expert panel advising the FDA.